Design, Development and Testing of Bent Axis Piston Pump

Transcription

1 Design, Development and Testing of Bent Axis Piston Pump Vijay V. Doijad 1 Amol B. Rabade 2, A.S. Todkar 3 P.G.Student, T.K.I.E.T. Warananagar 1,2 Professor, Department of Mechanical Engineering, T.K.I.E.T. Warananagar 3 ABSTRACT The hydraulic pumps found in virtually all mobile and industrial applications today use pistons, vanes, or gears to create the pumping action that produces flow. Each method features individual characteristics that differentiate it from the others and make it suitable for a particular range of applications. Piston pumps can have the pistons arranged in a radial or axial fashion. Axial piston pumps are available in a wide range of displacements and pressure capabilities that make them suitable for many mobile and industrial tasks. The bent axis piston pump designed, manufactured and tested. The pump has three pistons. Testing and trial of the piston pump to derive the performance characteristic of the pump drive namely, Discharge Vs Speed, Pressure Vs Speed, and Volumetric Efficiency Vs Speed. The volumetric efficiency is maximum 98.07% at 200 RPM. Keywords: Hydrulic pump, Bent axis piston pump, vanes, volumetric efficiency. 1. INTRODUCTION- Hydraulic pumps are used in hydraulic drive systems and can be hydrostatic or hydrodynamic. Hydrostatic pumps are positive displacement pumps while hydrodynamic pumps can be fixed displacement pumps, in which the displacement cannot be adjusted or variable displacement pumps, which have a more complicated construction that allows the displacement to be adjusted. Piston pumps can have the pistons arranged in a radial or axial fashion. Radial types tend to be specialized for applications requiring very high power, while axial piston pumps are available in a wide range of displacements and pressure capabilities that make them suitable for many mobile and industrial tasks. Axial-piston pumps consist of a set of pistons that are fitted within a cylinder block and driven by an angled swash plate powered by the input shaft. As the swash plate rotates, the pistons reciprocate in their respective cylinder Figure 1 Schematic Diagram of Bent axis piston pump block bores to provide the pumping action. Axial-piston pumps are available with the input shaft and pistons arranged coaxially, or with the input shaft mounted at an angle to the piston bore. Bent axis pumps tend to be slightly more volumetrically efficient. One end of each piston is held in contact with the cam plate as the cylinder block and piston assembly rotates with the driveshaft. This causes the pistons to reciprocate within the cylinders. The length of the piston stroke is proportional to the angle that the cam plate makes with the pump centerline. A unique characteristic of a pistontype pump is that the displacement can be changed simply by changing the angle of the swash plate. Any displacement between zero and maximum is easily achieved with relatively simple actuators to change the swash plate angle. Variable displacement pumps save power, increase the productivity or control the motion of a load precisely, safely and in an economical manner.the displacement varying mechanism and power to weight ratio of variable displacement piston pump makes them most suitable for control of high power levels. 2. ELEMENTS OF BENT AXIS PISTON PUMP The bent axis piston have number of elements. The major elements of bent axis piston pump are pistons, connecting rods, universal joint, flanges, input shaft, output shaft, bearings and motor. 3. MANUFACTURING- All component of machine are manufactured and assembled considering technical issues. These parts should be sufficiently rigid and equipped with special dampers in order to minimize vibrations. Volume 2, Issue 12, December 2013 Page 236

2 Three pistons are fitted within a cylinder block and driven by flange. The flange is driven by input shaft. The cylinder block is fixed in inclined position. This causes the pistons to reciprocate within the cylinders. Because of this reciprocating motion of pistons, oil is sucked and discharged. The angle of cylinder block is fixed so displacement is constant. Figure 2 Manufactured bent axis piston pump Figure 2 shows the bent axis piston pump. The power is given by 50 watt AC motor which is transferred to input shaft by belt drive. Figure 3 Experimental set-up Figure 3 shows the arrangement of bent axis piston pump parts. The flange and cylinder block is connected by universal joint. Piston and Flange is connected by connecting rod. Three pistons are connected by three different connecting rods. The speed of motor can be varying as per requirement. 4. TESTING- Testing and trial of the piston pump to derive the performance characteristic of the pump drive namely, Discharge Vs Speed, Pressure Vs Speed, and Volumetric Efficiency Vs Speed. Elements used for testing are 1. Flow Diverter valve (ball valve) 2. Adjustable relief valve 3. Flow measurement equipment 4. Pressure Gauge 5. Tachometer or RPM meter Figure 4 Working Bent axis piston pump Figure no. 4 shows the experimental setup of bent axis piston pump. The oil is used as a liquid. To avoid cavitations the bent axis piston pump is fixed inside the oil tank. The filter is fixed at the inlet port. The adjustable relief valve is attached to the outlet pipe. The pressure is measured by pressure gauge. Volume 2, Issue 12, December 2013 Page 237

3 4.1 Theoretical discharge from pump- Table 1 Theoretical discharge Sr. Speed Discharge( lpm) No Figure 5 Graph of Theoretical Discharge Vs Speed From the above graph it is clear that the discharge increases with the increase in pump speed, this increase is proportionate and shows minimal hysteresis ie, abrupt changes in flow characteristic are not seen, which is analogous to the hypothesis that the volumetric efficiency will be maintained even at high speeds. 4.2 Experimental derivation of discharge- Table 2 Actual discharge, pressure and volumetric efficiency Sr. No Speed Discharge( lpm) Pressure (bar) Volumetric efficiency Volume 2, Issue 12, December 2013 Page 238

4 Volumetric Efficiency at 800 rpm ηv = actual discharge x 100 Theoretical discharge = % = (1.94 ) x The average volumetric efficiency is η v avg = 89.81% Figure 6 Graph of Discharge Vs Speed Figure 7 Graph of Discharge Vs Pressure 4.3 Result & discussion: The above graph indicates that there is drop in output pressure with the increase in discharge, this drop is not substantial but analogous to the discharge characteristics of the pump, thus pump selection will be done considering the above characteristics and pressure requirement for application under consideration. 5. Conclusion The Bent axis piston pump is fabricated and satisfactorily working. Bent axis piston pump save power, increase the productivity or control the motion of a load precisely, safely and in an economical manner.the displacement varying mechanism and power to weight ratio of variable displacement piston pump makes them most suitable for control of high power levels. Volume 2, Issue 12, December 2013 Page 239

5 The bent axis piston pump is preferred in most hydraulic power systems because of its high performance and efficiency. It is also capable of operating at variable conditions of flow, pressure, speed and torque The following satisfactory conclusion are drawn after completion design, manufacturing and testing of the Bent axis piston pump Drop in output pressure with the increase in speed. The maximum pressure is 5 bar at 100 RPM and minimum pressure is 3.1 bar at 1000 RPM. Increase in discharge with increase in speed. The maximum discharge is 2.3 LPM at 1000 RPM The volumetric efficiency is maximum 98.07% at 200 RPM. References [1] Luo Xiaohui, Niu Zihua, Shi Zhaocun and Hu Junhua, Analysis and design of an axial piston water-pump with piston valve, Journal of Mechanical Science and Technology 25 (2) (2011) 371~378. [2] W.Kemmetm uller a, F.Fuchshumer b, A.Kugi a, Nonlinear pressure control of self-supplied variable displacement axial piston pumps, Control Engineering Practice 18 (2010) [3] Il-Hyun Baek1, Ihn-Sung Cho2, Jae-Youn Jung3,* and Lu Hong4, Analysis of piston behavior according to eccentricity ratio of disk in bent-axis type piston pump, Journal of Mechanical Science and Technology 22 (2008) 1726~1733. [4] Jong-Ki Kim, Jae-Youn Jung*, Driving Mechanism of Tapered Pistons in Bent-Axis Design Axial Piston Pumps, KSME International Journal, VoL 17No. 2, pp. 181~18~ [5] C. Ou-Yang and C. W. Chang, Developing an Integrated Intelligent Framework to Support an Engineering Change Process for an Axial Piston Pump Int J Adv Manuf Technol (1999) 15: Ó 1999 Springer-Verlag London Limited. [6] H.X. Chen, Patrick S.K. Chua, G.H. Lim *, Dynamic vibration analysis of a swash-plate type water hydraulic motor, Mechanism and Machine Theory 41 (2006) [7] Konrad Guggemos, Guenther Groeger, Richard Heingle, Herbert Leonhart, Axial piston pump or motor of the swashplate or bent axis type, United States Patent, Patent No. US8, 128,380 B2, Mar.6, [8] D. C. Hicks and C. M. Pleass, Development and testing of a composite/plastic high pressure seawater pump, Proc. of 1 st Bath Int. Fluid Power Workshop, Univ. of Bath, UK (1988) [9] J. A. Currie, The development of raw water hydraulics, Proc. of 1st Bath Int. Fluid Power Workshop, Univ. of Bath, UK (1988) [10] A. Brookes, The development of water hydraulic pump using advanced engineering ceramics, Proc. of 4th Scandinavian Int. Conf. on Fluid Power, Tampere, Finland (1995) Volume 2, Issue 12, December 2013 Page 240